Electric motor having stator with laminations configured to  form distinct cooling channels

ABSTRACT

An electric motor with a stator that is formed of a plurality of distinct laminations. Each of the distinct laminations has a radially inner lamination edge, which borders a rotor aperture configured to receive a rotor therein, a radially outer lamination edge and a plurality of cooling apertures formed there through that are disposed radially between the radially inner and outer lamination edges. Each cooling aperture in a lamination forms part of a separate and distinct cooling channel that extends helically through the laminations about a rotational axis of the electric motor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/151,719 filed Oct. 4, 2018, which claims the benefit of U.S.Provisional Patent Application No. 62/593,419 filed Dec. 1, 2017. Thedisclosure of each of the above-referenced applications is incorporatedby reference as if fully set forth in detail herein.

FIELD

The present disclosure relates to an electric motor having a stator withlaminations that are configured to form distinct cooling channels.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Electric motors are increasingly employed in applications such asvehicle propulsion where performance requirements as well as limitationson the size, mass and cost of the electric motor require that theelectric motor be actively cooled during its operation. More effectivecooling of an electric motor is desirable to further improve performanceof the electric motor and/or to reduce the size, mass and/or cost of theelectric motor.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

In one form, the present disclosure provides an electric motor thatincludes a stator, which is formed of a plurality of laminations, and arotor. The rotor is received in the stator and rotatable relative to thestator about a motor axis. Each of the laminations has a radially innerlamination edge, which borders a rotor aperture into which the rotor isreceived, and a radially outer lamination edge. Each of the laminationshas a plurality of cooling apertures formed there through. The coolingapertures formed in a given one of the laminations are disposed radiallybetween the radially outer lamination edge and the radially innerlamination edge. Each of the laminations is sealingly coupled to atleast one other lamination. Each cooling aperture in a lamination formspart of a distinct cooling channel that extends along an axial length ofthe stator. At least a portion of the cooling apertures in each of thecooling channels are staggered circumferentially about the motor axis.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a perspective view of an exemplary electric motor constructedin accordance with the teachings of the present disclosure;

FIG. 2 is an exploded perspective view of the electric motor of FIG. 1;

FIG. 3 is an elevation view showing a lamination of a stator of theelectric motor of FIG. 1;

FIG. 4 is a perspective, partly sectioned view depicting the presence ofcooling channels formed by the laminations that make up the stator ofthe electric motor of FIG. 1;

FIGS. 5A through 5E are elevation views depicting five uniquelaminations that are employed to form the stator of the electric motorof FIG. 1; and

FIGS. 6 and 7 are elevation views of two unique laminations that areformed of unique lamination segments.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With reference to FIGS. 1 and 2, an exemplary electric motor constructedin accordance with the teachings of the present disclosure is generallyindicated by reference numeral 10. The electric motor 10 includes astator 12 and a rotor 14 and can be any type of electric motor, such asa brushless DC electric motor or a type of AC induction motor, such asan asynchronous AC induction motor, for example. The rotor 14 isreceived in a rotor aperture 16 formed in the stator 12 and is rotatablerelative to the stator 12 about a motor axis 18. The stator 12 can beformed of a plurality of laminations 20.

With reference to FIGS. 3 and 4, each of the laminations 20 can have aradially inner lamination edge 22, which forms the border or edge of therotor aperture 16, and a radially outer lamination edge 24. Each of thelaminations 20 has a plurality of cooling apertures 26 formed therethrough. The cooling apertures 26 can be formed radially between theradially outer lamination edge 24 and the radially inner lamination edge22. Each cooling aperture in a lamination forms part of a distinctcooling channel 30 that extends along an axial length of the stator 12.The cooling channels 30 are configured to receive a cooling fluid therethrough during operation of the electric motor 10 to thereby cool thestator 12. At least a portion of the cooling apertures 26 in each of thecooling channels 30 can be staggered circumferentially about the motoraxis 18 so that coolant flowing through each of the cooling channels 30travels circumferentially through at least a portion of the stator 12 asthe coolant in the cooling channel 30 passes axially through the stator12.

With reference to FIGS. 5A through 5E, one means for achieving acircumferential offset in the cooling channels 30 is to employ aplurality of distinct laminations, such as laminations 20 a, 20 b, 20 c,20 d, and 20 e. The laminations 20 a, 20 b, 20 c, 20 d, and 20 e can beidentical but for their circumferential positioning of the coolingapertures 26 relative to a common datum 40. It will be appreciated thatthe cooling apertures 26 in the laminations 20 a, 20 b, 20 c, 20 d, and20 e can be circumferentially offset to a degree where the coolingapertures 26 in one of the laminations, such as lamination 20 e, partlyoverlap with the cooling apertures 26 in abutting laminations, such aslaminations 20 d and 20 a, but that the cooling apertures 26 in theabutting laminations (e.g., laminations 20 d and 20 a) either do notoverlap one another or overlap one another to a substantially smallerextent.

While the example shown in FIGS. 4 and 5A-5E employs five discretelaminations 20 a, 20 b, 20 c, 20 d, and 20 e that are arranged in arepeating sequence in which each lamination is disposed between twodifferently configured laminations, it will be appreciated that agreater or lesser number of discrete laminations could be employedinstead. Moreover, the laminations can be arranged in various othermanners. For example, the laminations can be arranged in sequences thatare partly made up of identical laminations that are disposed adjacentto one another. For example, the repeating sequence could include fiveof each of the discrete laminations 20 a, 20 b, 20 c, 20 d, and 20 e(i.e., a stack of five laminations 20 b is abutted on opposite sidesagainst a stack of five laminations 20 a and a stack of five laminations20 c, and a stack of five laminations 20 d is abutted on opposite sidesagainst a stack of five laminations 20 e and the end of the stack offive laminations 20 c that is opposite the stack of five laminations 20b) so that a sequence of the laminations consists of 20 a, 20 a, 20 a,20 a, 20 a, 20 b, 20 b, 20 b, 20 b, 20 b, 20 c, 20 c, 20 c, 20 c, 20 c,20 d, 20 d, 20 d, 20 d, 20 d, 20 e, 20 e, 20 e, 20 e and 20 e. Bystacking the discrete/different laminations in a desired manner (e.g.,in sequenced stacks), the surface area and path length can be balancedto the desired heat transfer rate(s) and pressure drop(s).

In FIGS. 2 and 4, each of the laminations 20 can be formed of anappropriate material, such as steel. If desired, each of the laminations20 can be formed to have preferentially oriented magnetic properties ina manner that is well known in the art.

Each of the laminations 20 can be sealingly coupled to at least oneother lamination 20. For example, the laminations 20 can be adhesivelybonded to one another. The adhesive that secures the laminations 20 toone another can seep between adjacent laminations 20 onto the edges ofthe cooling apertures 26 by an amount that coats the edges but does notclose any of the cooling apertures 26. Configuration in this manner canprovide additional strength to the bond between adjacent laminations 20,and/or provide a non-reactive barrier between the material of thelaminations 20 (i.e., steel in the example provided) and the coolantthat is intended to flow through the coolant channels 30.

With reference to FIGS. 6 and 7, each lamination could be formed from aplurality of lamination segments 50. In the particular example provided,each of the distinct laminations (e.g., lamination 20 a in FIG. 6 orlamination 20 c in FIG. 7) is formed from a plurality of identicallamination segments (e.g., lamination segments 50 a in FIG. 6 orlamination segments 50 c in FIG. 7) that are unique to the distinctlamination (i.e., lamination segments 50 a are employed only in theformation of lamination 20 a, while lamination segments 50 c areemployed only in the formation of lamination 20 c). Each of thelamination segments 50 can have a radially inner segment edge 22-1,which forms a portion of the radially inner lamination edge 22 of anassociated one of the laminations 20, a radially outer segment edge24-1, which forms a portion of the radially outer lamination edge 24 ofthe associated one of the laminations 20, and a pair of circumferentialsegment edges 60 that are each configured to abut a correspondingcircumferential segment edge 60 of an associated adjacent laminationsegment 50. A portion of the cooling apertures 26 in each lamination 20can be formed in each of the lamination segments 50 that make up thelamination 20.

The circumferential segment edges 60 can be formed in any desiredmanner/shape, but preferably do not intersect any of the coolingapertures 26. Optionally, the circumferential segment edges 60 of thelamination segments 60 in a given lamination 20 can be configured tointerlock a circumferential segment edge 60 of an adjacent laminationsegment 50 within the given lamination 20. For example, a first one ofthe circumferential segment edges 60 a on a given one of the laminationsegments 50 can form a tab, while a second one of the circumferentialsegment edges 60 b on the given one of the lamination segments 50 canform a tab aperture. The tap aperture can be configured to receivetherein the tab on the first one of the circumferential segment edges 60a on a circumferentially adjacent lamination segment 50.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

1. An electric motor comprising: a stator formed of a plurality oflaminations; and a rotor received in the stator and rotatable relativeto the stator about a motor axis; wherein each of the laminations has aradially inner lamination edge, which borders a rotor aperture intowhich the rotor is received, and a radially outer lamination edge, eachof the laminations having a plurality of cooling apertures formed therethrough, the cooling apertures being formed radially between theradially outer lamination edge and the radially inner lamination edge,each of the laminations being sealingly coupled to at least one otherlamination; wherein a plurality of separate cooling channels are formedin the stator, each of the separate cooling channels extending helicallyabout the motor axis along an axial length of the stator; wherein eachcooling aperture in a lamination forms part of an associated one of theseparate cooling channels; and wherein each of the separate coolingchannels is adapted to convey a flow of a cooling fluid helically aboutthe motor axis through the plurality of laminations without merging theflows of the cooling fluid from two or more of the separate coolingchannels within the plurality of laminations.
 2. The electric motor ofclaim 1, wherein each of the laminations comprises a plurality oflamination segments, each of the lamination segments having a radiallyinner segment edge, which forms a portion of the radially innerlamination edge of an associated one of the laminations, a radiallyouter segment edge, which forms a portion of the radially outerlamination edge of the associated one of the laminations, and a pair ofcircumferential segment edges that are each configured to abut acorresponding circumferential segment edge of an associated adjacentlamination segment, wherein a portion of the cooling apertures areformed in each of the lamination segments.
 3. The electric motor ofclaim 2, wherein a first one of the circumferential segment edges on agiven one of the lamination segments forms a tab and a second one of thecircumferential segment edges on another one of the lamination segmentsforms a tab aperture that is configured to receive therein the tab onthe first one of the circumferential segment edges on acircumferentially adjacent lamination segment.
 4. The electric motor ofclaim 3, wherein neither of the circumferential segment edges of any ofthe lamination segments intersects any of the cooling apertures.
 5. Theelectric motor of claim 2, wherein at least five distinct and differentlamination segments are employed over the axial length of the stator toform each cooling channel.
 6. The electric motor of claim 5, wherein thelamination segments that make up a given one of the laminations areidentical.
 7. The electric motor of claim 2, wherein each of thelamination segments is formed with preferentially oriented magneticproperties.
 8. The electric motor of claim 1, wherein each of thelaminations is formed with preferentially oriented magnetic properties.9. The electric motor of claim 1, wherein at least five distinct anddifferent laminations are employed over the axial length of the statorto form each cooling channel.
 10. The electric motor of claim 1, whereinat least a portion of the cooling apertures in each of the separatecooling channels are staggered circumferentially about the axis.
 11. Anelectric motor comprising: a stator having a lamination stack; and arotor received in the stator and rotatable relative to the stator abouta motor axis; wherein the lamination stack includes a plurality ofdistinct laminations; wherein each of the distinct laminations has aradially inner lamination edge, which borders a rotor aperture intowhich the rotor is received, and a radially outer lamination edge; andwherein each of the distinct laminations has a plurality of windingslots and a plurality of cooling apertures, the winding slotsintersecting the rotor aperture and being disposed in a winding slotpattern, the cooling apertures being disposed in a cooling aperturepattern, wherein the cooling aperture pattern of each of the distinctlaminations is rotationally offset from the winding slot pattern by adistinct pattern offset, and wherein a magnitude of the distinct patternoffset for each of the distinct laminations is different from thedistinct pattern offset for each of the other distinct laminations. 12.The electric motor of claim 11, wherein the plurality of distinctlaminations are arranged in a sequenced stack that is used a pluralityof times to form the lamination stack.
 13. The electric motor of claim12, wherein each of the plurality of distinct laminations is employed aplurality of times in each sequenced stack.
 14. The electric motor ofclaim 11, wherein the plurality of distinct laminations in thelamination stack are fixedly and sealingly coupled to one another. 15.The electric motor of claim 11, wherein each of the plurality ofdistinct laminations comprises a plurality of lamination segments, eachof the lamination segments having a radially inner segment edge, whichforms a portion of the radially inner lamination edge of an associatedone of the plurality of distinct laminations, a radially outer segmentedge, which forms a portion of the radially outer lamination edge of theassociated one of the plurality of distinct laminations, and a pair ofcircumferential segment edges that are each configured to abut acorresponding circumferential segment edge of an associated adjacentlamination segment, wherein a portion of the cooling apertures areformed in each of the lamination segments.
 16. The electric motor ofclaim 15, wherein a first one of the circumferential segment edges on agiven one of the lamination segments forms a tab and a second one of thecircumferential segment edges on another one of the lamination segmentsforms a tab aperture that is configured to receive therein the tab onthe first one of the circumferential segment edges on acircumferentially adjacent lamination segment.
 17. The electric motor ofclaim 16, wherein neither of the circumferential segment edges of any ofthe lamination segments intersects any of the cooling apertures.
 18. Theelectric motor of claim 15, wherein at least five different laminationsegments are employed over the overall length of the lamination stack toform each cooling channel.
 19. The electric motor of claim 18, whereinthe lamination segments that make up a given one of the plurality ofdistinct laminations are identical.
 20. The electric motor of claim 15,wherein each of the lamination segments is formed with preferentiallyoriented magnetic properties.
 21. The electric motor of claim 11,wherein each of the plurality of distinct laminations is formed withpreferentially oriented magnetic properties.
 22. An electric motorcomprising: a stator having a lamination stack; and a rotor received inthe stator and rotatable relative to the stator about a motor axis;wherein the lamination stack includes a plurality of first laminationsand a plurality of second laminations; wherein each of the first andsecond laminations has a radially inner lamination edge, which borders arotor aperture into which the rotor is received, and a radially outerlamination edge; and wherein each of the first laminations having aplurality of first winding slots and a plurality of first coolingapertures, the first winding slots being disposed in a winding slotpattern that defines a winding slot pattern datum, the first coolingapertures being formed radially between the radially outer laminationedge and the radially inner lamination edge of the first lamination andbeing arranged in a cooling aperture pattern that is oriented to thewinding slot pattern datum in a first manner, each of the secondlaminations having a plurality of second winding slots and a pluralityof second cooling apertures, the second winding slots being formedradially between the radially outer lamination edge and the radiallyinner lamination edge of the second lamination and being disposed in thewinding slot pattern, the second cooling apertures being arranged in thecooling aperture pattern but being oriented to the winding slot patterndatum of the second winding slots in a second manner that is rotatedabout the motor axis relative to the first manner.
 23. The electricmotor of claim 22, wherein the lamination stack includes a plurality ofthird laminations; and wherein each of the third laminations having aplurality of third winding slots and a plurality of third coolingapertures, the third winding slots being formed radially between theradially outer lamination edge and the radially inner lamination edge ofthe third lamination and being disposed in the winding slot pattern, thethird cooling apertures being arranged in the cooling aperture patternbut being oriented to the winding slot pattern datum of the thirdwinding slots in a third manner that is rotated about the motor axisrelative to the first manner and relative to the second manner.
 24. Theelectric motor of claim 23, wherein the first cooling apertures, thesecond cooling apertures, and the third cooling apertures form a coolingchannel that extends helically about the motor axis.